This is most likely an issue with your key, and torque you are applying to the key in different scenarios.
Be careful when you turn your key opening your gas tank, and seat. Pushing down on seat is a good idea when first opening it, when you are opening your gas tank, make sure you are not yanking on the key to pull up the gas cap, pull the gas cap itself.
The ignition is very finicky about your honda key, if it is only slightly bent out of shape, sometimes you will only be able to insert the key on one side to turn, like my key is doing right now. If i put it in one orientation, it will not move at all, if i put it in the other orientation, it will.
I caused this problem one day when i went to get gas, my gas cap is pained black, and occasionally it sticks a bit when pulling up, i made the mistake of pulling on the key, instead of the gascap, and i bent my key way out of shape.
I was able to insert it back into the gas cap, and bend and check, and bend and check, and i finally got it back into a shape that will work consistently with one orientation.
Hopefully you have a spare, if not, get a copy made asap, but test your key out and see which orientation works better, if at all.
Good luck to you.